A man is being sought over the discovery of a child's skeletal remains in scrub east of Adelaide.
Police believe the child was murdered, but are yet to determine the sex or identity.
Their investigations are now centred on a man who was spotted carrying a suitcase in the area six to eight weeks ago.
"That person was about 60 years of age, of average height, lightly built and neatly dressed and clean cut.... he was carrying a dark-coloured suitcase in one hand," Superintendent Des Bray told reporters on Thursday.
They want him to make contact with detectives and have also called for anyone who saw him in the Wynarka area to come forward.
A motorist found both the child's remains and a suitcase off the Karoonda Highway, east of Adelaide, on Tuesday, but did not alert police until Wednesday.
Police believe the child, aged between two and seven, was killed some time before the discovery.
The body was then placed in the suitcase, which was left alongside the highway, possibly more than two months ago.
"The suitcase was concealed behind a bush. One person that stopped has removed the suitcase and dropped it out into a more open position," Supt Bray said.
"Other people over the last, we assume, couple of months, have stopped to have a look at it.
"People have opened it and some people have had a bit of a poke around."
A variety of items were found in the suitcase, but police have not disclosed what they are.
Officers and volunteers on Thursday conducted an extensive search of the surrounding bush.
Homes in Wynarka were also doorknocked and vehicles travelling on the highway were stopped.
A post-mortem examination is being conducted.
